Tricon Consulting

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Dear seniors, I would appreciate your help in analyzing an issue: The system built into the unit consists of 4 AI cards of type 3721 (with 32 channels each) and 8 AI-ETP cards of type 9771. These have been in use for nearly five years, and recently, the data from three of the AI cards began to fluctuate (by about 1S, before returning to normal quickly). No abnormalities were found upon on-site inspection; the fluctuating signals came from different junction boxes, the system’s grounding was proper, and there were no issues with the 220V and 24V power supplies. Additionally, a 4-20mA signal sent from the DCS in the cabinet also exhibited fluctuations. The remaining AO/DI/DO cards are functioning properly. It is suspected that there may be a problem with the power supply on the backplanes of these three cards. I hope you can help analyze this issue